If you’re trying to follow a diet that builds and supports a healthy gut microbiome, finding which foods contain the right microorganisms and nutrients (probiotics and prebiotics) and in the recommended amounts can be tricky.
Good news: Research presented at Nutrition 2023, the annual meeting of the American Society of Nutrition, does much of the heavy lifting by revealing the foods with the highest amounts of prebiotics.
After examining the prebiotic content of thousands of foods, researchers have revealed the foods that pack the greatest prebiotic impact:
As a bonus, in addition to supporting gut health, prebiotic-rich foods contain high amounts of fiber, which has been shown to support gut health, keep you regular, and help you feel fuller for a longer period of time, according to the U.S. Food and Drug Administration (FDA).
Consuming prebiotic-rich foods has been shown by previous research to benefit health, study co-author Cassandra Boyd, a master’s student at San Jos State University in California, said in a news release. Eating in a way that promotes microbiome health while eating more fiber may be more attainable and accessible than you think, she added.
Prebiotics and probiotics: what they are and why they are important
Prebiotics are sometimes equated to dietary fiber, but only a subset of dietary fiber qualifies as a prebiotic, according to the International Scientific Association for Probiotics and Prebiotics (ISAPP).
Prebiotics are a type of dietary fiber that we, the host, can’t digest, but select microbes in the gut microbiota can, explains Gail Cresci, PhD, RD, microbiome researcher at Cleveland Clinic Childrens in Ohio.
This means that prebiotics escape digestion and travel to the colon, where select members of the gut microbiota are able to digest them. Because of this, prebiotics are able to support optimal gut microbiota composition, and this interaction can produce metabolites that have health benefits, says Dr. Grow up.
Prebiotics are different and shouldn’t be confused with probiotics, live microorganisms found in fermented foods like fermented milk and yogurt, tempeh, miso, sauerkraut and salty drinks that can help improve microbiome diversity, according to the National Institutes of Health.
Think of it this way: Prebiotics are food for the microbiome, while probiotics contain live microorganisms. Both have the potential to benefit microbiome health, but they work in different ways.
What is a Jerusalem artichoke, also known as a sunchoke?
Despite its name, the Jerusalem artichoke (Helianthus tuberous ) has no connection to Jerusalem and is not even an artichoke, according to the University of Michigan; the plant is related to sunflowers. Its edible tuber, also known as sunchoke, is a knobby root vegetable resembling ginger that tastes similar to a nutty sweet potato.
A healthy and diverse microbiome supports overall health and can reduce the risk of obesity and other chronic diseases
We’re still learning, but current evidence suggests that the gut microbiome supports overall health and well-being through its role in digestion, production of beneficial metabolites, support of immunity, exclusion of pathogens and maintenance of intestinal barrier function, says Cresci, referring to a review published inSignal transduction and targeted therapy in April 2022.
There is also some evidence associating a lack of microbiome diversity with obesity and obesity-related diseases such as type 2 diabetes, according to a paper published in March 2022Biomedicine and Pharmacotherapy .
Which foods contain the most prebiotics?
For the study, the researchers used previously published scientific findings to analyze the prebiotic content of more than 8,000 foods contained in the Food and Nutrient Database for Dietary Studies, a resource many scientists use to study nutrition and health.
Of these foods, more than a third contained prebiotics. Dandelion, sunchoke, garlic, leeks and onions had the highest amounts, ranging from about 100 to 240 milligrams of prebiotics per gram of food (mg/g).
Other prebiotic-rich foods included onion rings, creamed onions, cowpeas, asparagus and Kellogg’s All-Bran cereal, each containing 5060 mg/g.
Items containing wheat rank further down the list. Foods with little or no prebiotic content include dairy products, eggs, oils and meats.
Findings from the preliminary literature review suggest that onions and onion-related foods contain multiple forms of prebiotics, according to the authors.
Multiple forms of onions and related foods appear in a variety of dishes as both condiments and main ingredients. These foods are commonly eaten by Americans and therefore would be a viable target for people to increase their prebiotic consumption, Boyd said.
Here’s how much you need to eat to get the recommended amount of prebiotic foods
While most dietary guidelines do not currently specify a recommended daily allowance for prebiotics, ISAPP recommends an intake of 5g per day. The recommended amount of fiber is 28 g per day based on a 2,000 calorie per day diet.
To get the minimum intake of 5 g of prebiotics, a person would need to eat about half of a small onion (4 ounces), 6 or 7 cloves of garlic, a quarter of a medium leek, a cup of dandelion greens or a quarter of a sunchoke.
Does cooking foods change their prebiotic content?
One limitation of the study was that we made some assumptions about the raw and cooked variations of some foods containing the same prebiotic content, Boyd says. That’s because there’s limited research on how the prebiotic content of foods is affected by cooking, he explains.
Because prebiotics are a type of fiber, various cooking methods can reduce the fiber content of your food, Cresci says. Eating the food raw or cooking it lightly would better preserve the prebiotic content, he says.
Although the prebiotic content decreases with cooking, prebiotics are still present. This means that by consuming a larger serving of these cooked foods, there will likely still be enough prebiotics present to provide a health benefit, Boyd says.
Expert advice on how to increase your prebiotic intake
If you suspect you’re not getting enough prebiotics, it’s best to start with small amounts and gradually increase your portions and the number of servings per day, according to Monash University. By giving your gut and its bacteria more time to adjust, you won’t feel gassy or bloated.
Children’s Hospital of Philadelphia recommends a mix of plant-based foods that contain naturally occurring prebiotics, along with foods that have been fortified with them. Prebiotics are sometimes added to food items such as yogurt, cereal, bread, cookies, desserts or beverages, according to ISAPP. The word prebiotic is not always used on the label; instead, look in the ingredients list for galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), oligofructose (OF), chicory fiber, or inulin. Alternatively, prebiotics can be taken in supplement form.